The Improv Wiki

Closer

The line that ends the scene.

A good closer makes all the previous action seems to have been for a purpose, which is now fulfilled. It makes the scene seem like it has reached a natural and proper ending.

How do you learn to make a good closer?

Coming up with a good closer is one of the more difficult Improv Skills to acquire. An exercise to learn it is Three Line Scene.

An opposing idea: maybe closers are a bad idea

Some improvisers think the notion of a "closer" is completely ridiculous, and don't try to write while they improvise.

Indeed, when you say a line with the intention of it closing the scene, you may well be disappointed if the lights don't go out right then. And then you can be stuck for a next line, since your mind got out of the scene.